1. Field of Technology
The present invention relates to a sewage cleaning apparatus intended for water clarification and solid-liquid separation, and in particular, relates to a magnetic separation filtering and cleaning apparatus for trapping magnetic materials by a membrane and magnetically separating trapped materials.
2. Prior Art
There is a well-known magnetic separation sewage cleaning apparatus (for example, see Japanese Application Patent Laid-open Publication No. 2002-273261) in which a net woven out of thin wires or polymeric fibers is used as a water separation membrane for the purpose of solid-liquid separation, flocculant and magnetic powder are added to raw water containing pollutant particles to form  magnetic floc, the magnetic floc is separated by the membrane, and the magnetic floc trapped by the membrane is magnetically removed by a magnetic field generation means, thereby recovering highly concentrated sludge.
The above-mentioned membrane separation cleaning apparatus is equipped with a net woven out of stainless-steel thin wires or polyester fibers, and has, for example, a membrane molecular portion having a several tens of micron-meter mesh opening. In order to separate microscopic pollutants smaller than the projected area or a projected diameter of the opening, for example, aluminum sulfate, polyaluminum chloride, iron polysulfate, and magnetic powder are beforehand added to raw water as flocculant and stirred so that microscopic suspended solids, algae, fungi, and microorganisms contained in raw water are flocculated by a flocculant to form several hundred micron meter magnetic floc. The magnetic floc cannot pass through the opening of a several tens of micron meter mesh and is trapped and separated at a high elimination ratio, and the water filtered through the membrane becomes high-quality clarified water.
Magnetic floc trapped on the membrane is washed off from the membrane by cleaning water. Then, magnetic floc which remains on and around the surface of the water is suctioned by a magnetic force of a magnet immobilized near the water surface, magnetically separated, and transferred  by a sludge transfer device to a sludge recovery tank and eliminated. Eventually, sludge is normally carried by a truck to a repository site or an incineration site or made into compost.